About 50 species: N Asia, E Europe, and especially diverse in the Himalayan region and W China; 39 species (22 endemic) in China.

This is a widespread, heterogeneous genus of complex and controversial taxonomy. Russian authors delimit Pleurospermumsensustricto by only two species (the type, P. austriacum Linnaeus, and P. uralense), referring the other species to Aulacospermum, Hymenidium, Hymenolaena, Physospermopsis, and Pterocyclus. Other morphologically similar genera, where generic boundaries become indistinct, include Trachydium and Pseudotrachydium (Kljuykov et al.) Pimenov & Kljuykov. A full discussion of the Russian classification of Pleurospermum is presented by Pimenov and Kljuykov (Feddes Repert. 111: 499–515, 517–534, 535–552. 2000). As yet, this rather radical classification has not gained widespread acceptance, and the proponents admit that this is a taxonomic hypothesis, and (particularly for some groups) a more natural classification will only be possible following critical revision in the field and herbarium. A traditional treatment is adopted for the following account, with due influence from the work of the Russian taxonomists.

The following species have been described from Chinese material, but are imperfectly known as no specimens have been seen or the specimens are inadequate.